<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,user-scalable=no, initial-scale=1">
    <title>Title</title>
    <link rel="stylesheet" href="citySelect.css">
    <script src="cityData.js"></script>
    <script src="citySelect.js"></script>
</head>
<body>
<input type="text" class="in">
<script>
    _citySelect({
        elem:document.querySelector('.in')
    })
</script>
</body>
</html>